OP - my graduate research was on submerged / floating leaf aquatics near Fairfield, and included several of the plants you mentioned. I recommend finding a pond with some combination of southern naiad (Najas guadalupensis), coontail (Ceratophyllum demersum), and any of the pondweeds (Potamogeton sp.).
You can use a rake to get a bunch in a cooler and then shove handfuls down into the wet soil, preferably in areas that will stay between 6-18" of water.
I would avoid musk grass (Chara), which is actually a complex algae. It will tend to dominate ponds that have high nutrient inputs, from cattle or fertilizer. It is really only good for invertebrate habitat, as dabbling ducks don't choose this as forage over the others. I this is the only thing they have available, you probably don't want to eat them anyway. Coontail is a native plant that provides similar habitat value for invertebrates (high value for hens in late season).
Sago pondweed does occur in Texas, but it is fairly rare compared to several other pondweed species. I used this in my research, and the other pondweed species outperformed it for biomass production in the water / soils about 1 hour north of B/CS.
Widgeon grass (Ruppia maritima) is a coastal species that doesn't do well in fresh water. It has been a while since I looked at it, but I'm guessing if you're not in an intermediate marsh with 3-10 ppt salinity, you're not going to get it to grow.
If you ever want to chat about submergents, shoot me a note. My email is in my profile, but I can't message due to no stars.